As a modern industrial society advances, a city area expands, so a water contamination problem among numerous environment problems becomes a key factor which might consequently threaten the future of mankind. As a way of overcoming the above problems, a contamination substance discharge permission criteria is being reinforced, and a biological or physicochemical, advanced treatment facility is increasingly used. In particular, various types of filtration devices are proposed and used in order to enhance the quality of final effluent in the advanced treatment facility for sewage and wastewater.
Among the most widely used methods in terms of the filtration device, there are the Korean patent registration publication numbers 0121118 “FILTERING APPARATUS OF SEPTIC TANK”, the registration number 10-0438150 “Back Fresh Method Using Influent Water Head and Filter Apparatus Employing the Same”, the registration number 10-0479476 “for reusing waste water using drum filter and vortex filter”, and the registration utility model publication number 20-0222527 “Filtering device of wastewater having multi filtering layer therein”, in each of which filtration devices, the filtration layer is formed of inorganic particle substances such as sand, anthracite, activated carbon, clay, ground magnetite, garnet, inactive medium or something, thus filtering inflowing water.
The above conventional filtration device however is disadvantageous because a collection space of underwater particles is limited to a water surface portion as compared with an installation area, and since it is equipped with a fixed porosity structure depending on the characteristic of a filter medium, a porosity decrease in a filtering layer and a porosity clogging problem often occur due to the floating substances in underwater. The above filtration device increases pressure head loss due to a filtration resistance, which consequently causes a flow channeling phenomenon, a break-through phenomenon, etc., so a reverse washing frequency and a reverse washing amount increase in the filter medium of a filtration layer. The filtration speed is low because the filtration pressure is large due to the filled filter medium, and the filter medium might be leaked during reverse washing.
Some filtration devices using a fiber yarn as a filter medium are disclosed so as to improve the problems encountered in the above filtration devices. There are Korean patent publication numbers 1997-0007944 “APPARATUS OF FILTRATION”, the patent registration number 10-0241198 “VARIABLE PORE MICRO FILTER”, the Korean patent number 10-0324727 “Separating apparatus of suspended solid in liquid solution using flexible fiber”, the Korean patent number 10-0354836 “Apparatus for filtering suspended solid in water”, the Korean patent number 10-0362594 “Pore Size Controllable Filter”, etc.
Since the above filtration devices are difficult to control pores when forming pores by controlling a fiber yarn, it is difficult to randomly adjust water quality and water amount when the quality of inflowing water varies. Besides, the conventional filtration devices have problems maintaining an adhering force between fiber yarns.